1. Technical Field
This invention relates to a water repellent glass treatment for automotive applications comprising a windshield washer solvent which contains quaternary compounds, preferably siloxane based quaternary ammonium compounds, fatty quaternary ammonium compounds, and mixtures thereof which are dispersible in water, alcohol""s and water alcohol mixtures and imparts a good degree of hydrophobicity to the windshield surface.
2. Description of the Prior Art
Modern automobiles require frequent attention to the windshield to insure safe operation. The glass must be kept reasonably clean for visibility. Wipers frequently need to be replaced to maintain wet weather visibility while driving, particularly at night. While water can be used in the underhood reservoir for cleaning the windshield during warm weather, the year round need for greater detergency to remove oil, deposits, bird droppings and insect matter dictates the use of a solvent based system. Typically, these systems include a surfactant and are methanol-water based to offer improved freeze protection for the winter. Bittering agents, like denatonium benzoate, are often used. Sometimes isopropyl alcohol is used in conjunction with methanol-water for freeze point depression. In Europe ethanol-water based systems are used for lower mammalian toxicity. Freeze points in the 20xc2x0 to xe2x88x9240xc2x0 F. range are common. Dye is often added to allow level recognition in opaque reservoir bottles. Blue is typically used in North American but examples span the palette of color possibilities. Thermal and UV stability are required as well as basic solubility, plastics compatibility and minimal staining.
Conventional windshield cleaner treatments fail to make the glass windshield repel water in outside environments and require constant replenishment. U.S. Pat. No. 3,940,588 teaches coating with hydrolyzable di-silyl poly(perflourooxyalkene) to produce oil and water repellent coatings. U.S. Pat. No. 4,410,563 covers water repellent coatings for optical surfaces including windshields based on Dow Corning 531 and 536 fluids, amino functional polydimethylsiloxane. These approaches require treatment of the subject surface by hand to obtain the coating. The coatings would have to be reapplied at some future point to maintain the water repellent effect. Clark teaches a storage stable water repellent based on an acid neutralized cationic polysiloxane copolymer containing aminofunctional groups in U.S. Pat. No. 3,639,131. The ""131 patent is primarily concerned with making an aluminum can storage stable mixture by heating. This mixture is applied to a windshield during rain to render it water repellent. Treatments to modify the glass and make it repel water have also been taught in U.S. Pat. No. 5,415,927 wherein Hirayama uses organic silicon and fluorine compounds to form water repellent layers. These conventional windshield washer solvents fail to provide an instant water repellent automotive glass surface without extensive pretreatment or application surface preparation. Moreover, none of these conventional windshield additive formulas added to a primarily aqueous system utilize a quaternary compound to repel water as does Applicant""s invention.
The instant invention provides a water repellant fluid used in traditional underhood washer solvent reservoirs filled with water or alcohol/water blends with or without detergents, and applied by simply pressing a cabin button to squirt the liquid on the windshield. This eliminates the need for polishing the windshield ahead of time.
It is an object of the present invention to provide a water repellant fluid that is soluble or dispersible in water, alcohols and mixtures of water and alcohols.
It is an object of the present invention to provide a water repellant fluid which does not exhibit build up with repeated use, streak or stain windshields or damage paint.
It is an object of the present invention to provide a water repellant fluid having a pH range of from about 6.0 to 9.0 and more particularly in a range of from about 7.0 to 8.0.
It is an object of the present invention to provide a water repellant fluid which is thermally stable in view of underhood temperatures which can approach 150xc2x0 F.
It is an object of the present invention to provide a water repellant fluid which does not separate on standing.
It is an object of the present invention to provide a water repellant fluid which does not have objectionable toxicological properties.
It is an object of the present invention to provide a water repellant fluid which does not have objectionable odor.
It is an object of the present invention to provide a water repellant fluid which is compatible with conventionally available washer solvents.
It is an object of the present invention to provide a water repellant fluid which is environmentally benign.
It is an object of the present invention to provide a water repellant fluid which does not negatively impact vision even at night.
It is an object of the present invention to provide a water repellant fluid which will provide a wetting surface having a contact angle which is greater than that of water.
It is an object of the present invention to provide a water repellant fluid which provides a wetting surface having a contact angle which is greater than that of water upon adding at least 0.001 percent of said water repellant fluid to a solvent of water, alcohols, or a water and alcohol mixture.
It is an object of the present invention to provide a water repellant fluid when added to a windshield washer solution in an amount of between 0.001 percent and 1.0% by volume.
It is an object of the present invention to provide a water repellant fluid which provides a wetting surface having a contact angle greater than that of water having a contact angle of from 10 to 15 degrees, when the concentrate is diluted to 15 percent by volume of less with water, alcohol or combinations thereof.
It is another object of the invention to prepare a concentrate which can be diluted to a 1 percent by weight solution when added to a water, alcohol, or water and alcohol mix providing an effective water repelling surface treatment.
It is another object of the invention to provide a concentrate which can be diluted to a 1 percent by weight solution in a water and alcohol mixture containing alcohol in amounts ranging from 5 to 50 weight percent and provide an effective water repelling surface treatment.
These and other objects of the present invention will be more fully understood from the following description of the invention.
A water repellent glass treatment for automotive applications comprising a windshield washer treatment which contains a quaternary compound, preferably a siloxane based quaternary ammonium compounds, fatty quaternary ammonium compounds, and mixtures thereof which are dispersible in water, alcohol""s and water alcohol mixtures and imparts a good degree of hydrophobicity to the windshield surface which traditiionally consists of a glass substrate or clear or translucent polymer.
Any of a large group of siloxane polymers based on a structure consisting of alternate silicon and oxygen atoms with various organic radicals attached to the silicon. 
A straight-chain compound consisting of silicon atoms single-bonded to oxygen and so arranged that each silicon atom is linked with four oxygen atoms. 
In particular, polydimethyl siloxane based quaternary ammonium compounds with molecular weights ranging from about 300 to about 500,000 and C8-C24 fatty based quaternary compounds, either on their own or preferably in combination thereof, which is dispersible or soluble in water or alcohol, or in water and alcohol mixtures. Moreover, these compounds individually or together may be made dispersible or soluble in water, alcohol, or mixtures thereof through the use of various emulsifiers or cosolubilizers which impart a good degree of hydrophobicity to the windshield surface.
Fatty quaternary compounds are typically quaternary ammonium salts which are a type of organic nitrogen compound in which the molecular structure includes a central nitrogen atom joined to four organic groups (the cation) and a negatively charged acid radical (the anion). The structure is indicated as: 
The C8-C24 fatty quaternary compounds include mono and/or di-alkyl amido amine quats, imidazoline quats, di-amido quats, di-methyl ammonium chloride quats, tri-methyl ammonium chloride quats, di-methyl benzyl quats, and other fatty quaternary compounds. Pentavelent nitrogen ring compounds, such as lauryl pyridinium chloride, are also considered quaternary ammonium compounds. They are all cationic surface-active coordination compounds and tend to be adsorbed on surfaces.
Optionally, other components including dyes, such as LIQUITINT teal dye, in amounts ranging from 0.1 to 1.0 percent by weight; bittering agents, such as BITTREX EA, in amounts ranging from 0.1 to 3.0 percent by weight; biocides; and the like may be added to the present formulation.
One embodiment of the present invention consists of a quaternary ammonium salt of a polydimethyl siloxane with a fatty acid and a weight distribution range of from between about 300 and 2000 which is dispersible in water, alcohol""s and water alcohol mixtures.
Another preferred water repellant compound comprises both a water dispersible high molecular weight polydimethyl siloxane based quaternary ammonium compound and a water dispersible C8-C24 fatty based quaternary compound having a cationic functional group in an alcohol solvent sold under the trademark of PR 1145 manufactured by Siltech Corporation of Toronto, Canada. The high molecular weight polydimethyl siloxane compound is present in an amount up to 85 percent by weight and more preferably from between 0.1 and 85 percent by weight and the water dispersible C8-C24 fatty based quaternary compound having a cationic functional group is present in an amount up to 50 percent by weight and preferably from between 0.01 and 50 percent by weight; an alcohol solvent such as dipropylene glycol ranging in an amount of from about 1 to 50 percent and preferably in an amount ranging from about 5 to 35 percent by volume is incorporated therein. A surfactant, such as a silicon surfactant may optionally added to the composition in amounts ranging from 0.001 to about 10 percent; and water.
Yet another preferred embodiment of the present invention is a water repellant treatment concentrate for dilution with a windshield washing solvent, wherein the concentrate comprises a combination of a high molecular weight silicon quaternary compound and an alkanolamide, a nonsilicon quaternary compound. The high molecular weight silicon compound is present in an amount of from between 0.01 and 99 percent by weight and the alkanolamide is present in an amount of from between 0.01 and 99 percent by weight; more preferably the high molecular weight silicon compound is present in an amount of from between 5 and 85 percent by weight and the alkanolamide is present in an amount of from between 5 and 95 percent by weight; more preferably wherein the high molecular weight silicon compound is present in an amount of from between 55 and 65 percent by weight and the alkanolamide is present in an amount of from between 5 and 45 percent by weight. Moreover, the high molecular weight silicon compound may be is a solution of an alcohol such as dipropylene glycol ranging in an amount of from about 0.1 to 50 percent and preferably in an amount ranging from about 5 to 35 percent and more preferably in an amount ranging from about 15 to 20 percent by volume. A surfactant, such as a silicon surfactant may be added to the composition in amounts ranging from 0.001 to 10 percent and preferably from about 0.01 to 6 percent.
Typically, a preferred embodiment would comprise a high molecular weight silicon quaternary compound in an amount ranging from about 45 to 65 percent in a dipropylene glycol solvent in an amount ranging from about 5 to 35 percent, combined with an alkanolamide in amount ranging from about 5 to 35 percent, and a surfactant in an amount ranging from about 0.01 to 10 percent.
Selection of a water dispersible high molecular weight polydimethyl siloxane based quaternary ammonium compound and a water dispersible C8-C24 fatty based quaternary compound having a cationic functional group provides a method of interacting with the glass substrate. The glass substrate such as a windshield of an automobile or canopy or an airplane, are anionic in nature stemming from partially charged bridging and fully charged terminal oxygens in the borosilicate glass network. The quaternary compound""s cationic functional group, (xe2x80x9cheadxe2x80x9d), adheres to the anionically charged glass. The hydrophobic functional group of the compound, (xe2x80x9ctailxe2x80x9d), repels water at the interface. The mechanism is limited in that once the charge on the glass is compensated, further buildup beyond the molecular layer is limited. A second molecular layer of tail to tail interaction is theoretically possible, but is so weakly bound that it, and higher order interactions can be ignored providing a thin film which increases the contact angle and hydrophobicity of the surface and still resists buildup.
As set forth in Table 1, the contact angles of quaternary compounds suitable for use for increasing the contact angle of the surface above that of water are shown in a 1.0% solution, a 100 parts per million, (ppm), (0.01%) solution, and a 200 ppm (0.02%) solution. More particularly, the embodiments of polydimethyl siloxane based quaternary ammonium compounds and water dispersible C8-C24 fatty based quaternary compounds are selected from the group comprising: A. SILQUAT D10-B, a low molecular weight silicon quat; B. SILTECH NS SAQ, a nonsilicon alkyl amido dimethyl quat; C. a blend of a low molecular weight silicon quat and a nonsilicon alkyl amido dimethyl quat; D. SILQUAT J15-NO, a blend of a nonsilicon dialkyl amido amine quat and a high molecular weight silicon quat; E. a nonsilicon dialkyl amido amine quat; F. SILQUAT J15-NO, a high molecular weight silicon quat; G. a blend of a high molecular weight silicon quat in a dipropylene glycol solvent and a dialkyl amido amine quat; H. SILQUAT J15-B, a high molecular weight silicone quat in an alcohol solvent; I. SILQUAT J15-D, a high molecular weight silicone quat in a dipropylene glycol solvent; J. SILQUAT J15-D-60, a high molecular weight silicone quat; K. a blend of SILQUAT J15-B and a dialkyl amido amine quat; L. SILQUAT NS SAQ, a 50/50 blend of SILQUAT J15-B, a high molecular weight silicone quat in an alcohol solvent, and an alkyl amido dimethyl quat; M. SILQUAT NS SAQ, a 80/20 blend of SILQUAT J15-B, a high molecular weight quat in alcohol, and an alkyl amido dimethyl quat; N. a high molecular weight silicone quat and a alkyl amido dimethyl quat; O. a dialkl diamido quat; P. a dialkyl imidazoline quat; Q. an alkyl dimethyl benzyl quat; R. a dialkyldimethyl quat; S. an alkyl trimethyl quat; and T., a blend of SILTECH J15-B high molecular weight silicone quat in an alcohol solvent and alkanolamide.